1. Field of the Invention
The present invention generally relates to a control apparatus of an automatic door. More specifically, the present invention relates to a control apparatus of an automatic door in which the opening amount of the door can be changed.
2. Description of the Prior Art
A conventional automatic door has been generally structured such that an opened amount is predetermined, which is usually the amount for a full-opened state. Therefore, each time a door is opened cooled air or warmed air generated by an air-conditioning apparatus in a building is dissipated outside the building. As a result, the recent demand of energy savings has not been fully met. Therefore, previously the present inventors have proposed a control apparatus of a door in which a maximum opening amount of a door can be changed not only to that for a full-opened state but also to that for a half-opened state. However, the previously proposed automatic door which constitutes the background of the present invention comprises two position detecting sensors such as reed switches for detecting positions where a door is to be stopped in opening the same, in order to detect such positions for full-opened state and half-opened state such that one of them is selectively enabled to control an opening amount of such as a full-opened state or a half-opened state. Therefore, with such background technology, it is required to provide a plurality of reed switches for detecting stop positions, which necessitates an increased number of components and hence makes the structure complicated and makes installation troublesome.
The above described previously proposed background technology further involves a disadvantage that when an abnormal load is applied to a door in opening the door to a half-opened state no brake cannot be applied to the door, which could result in damage of the door eventually. The reason is that in the case where a door is to be half-opened those reed switches to be enabled in opening the door to a full-opened state have been disabled as a matter of course. More specifically, if and when those reed switches to be enabled in opening a door to a full-opened state are enabled the fact that the door was opened to a full-opened state by an abnormal load is detected, whereupon a brake is applied to the door. However, in such a case where only the reed switch for opening a door to a half-opened state is enabled, a door being about to be opened to a full-opened state cannot be subject to a brake function eventually inasmuch as no means for detecting the same has been provided.